Contact lenses made from silicone hydrogels are rapidly gaining popularity over contact lenses made from conventional hydrogel materials because, like conventional hydrogel lenses, they are comfortable to wear, but they have the added advantage of having higher oxygen permeability, which is believed to be healthier for the eye. However, contact lenses made from silicone hydrogels often have physical properties that make them more difficult to process during manufacturing and reduces the shelf-life of the final product. New formulations of silicone hydrogel contact lenses that are easier to manufacture and have increased stability are desired.
Some patent documents describing silicone hydrogel contact lenses include U.S. Publ. No. 2007/0296914, U.S. Publ. No. 2007/0066706, U.S. Publ. No. 2007/0231292, U.S. Pat. No. 5,965,631, WO 2011/041523, U.S. Pat. No. 5,358,995, European Publ. No. 1870736A1, U.S. Publ. No. 2006/063852, U.S. Publ. No. 2011/0009587, and U.S. Publ. No. 2009/0234087.